Environmental testing of materials involves exposing a test piece of a material to a specific environment (chemical, thermal, etc.) in order to reveal any adverse effects of that environment on its properties, and in particular on its mechanical properties. When one of the properties of the material that needs to be analyzed is its ability to withstand propagation of an existing defect, e.g. a surface crack, it is necessary to be able to subject the test piece to mechanical stresses, e.g. in traction. Applying and varying stresses, and also observing propagation of the defect, require the test piece to be accessible during testing. This raises a problem when the test piece must simultaneously be exposed to a test environment that is corrosive, toxic, flammable, and/or likely to be contaminated.
In the prior art, it is known to carry out mechanical tests on a test piece placed inside a leaktight receptacle in which the desired test environment is created (e.g. the presence of corrosive vapor). That method makes it possible, in satisfactory manner, to control the physico-chemical characteristics of the test environment (pressure, temperature, chemical composition, . . . ), but it presents the drawback of making the test piece inaccessible throughout the duration of the test.
It is also known to carry out tests on a test piece in which a portion of its surface is exposed to a flow of a potentially corrosive composition in the liquid or gaseous state. In that way, the test piece can be accessible in part during the test, but the characteristics of its environment are difficult to control, and in general cannot faithfully reproduce the real conditions encountered on a mechanical part while it is in use. In addition, that approach is difficult to implement with compositions that are dangerous (toxic, flammable, explosive, . . . ) or that might be contaminated.